Telephone system



Oct. 29, 1929. H, B, JOHNSQN 1,733,602

TELEPHONE SYSTEM Filed May 12, 1925 by ,my

Patented Oct. 29, l1929 UNirsie STATES YORK n y ,v Application fliedkMay 12,k

This invention relates to telephone systems and particularly toimprovementsin the supervision of straightforward trunking connectionsestablished through tandem trunks.

In prior systems of this type where connections are established from asubscriber in a local exchange through an A operators cord circuit, atandem trunk terminating at a tandem exchange through an Outgoing trunkto a called subscribers station, the A operator is notiied by theextinguishing of the superswers the call by removing his receiver fromthe hook. This indication is usually given by the reversal'offthebattery over the tip and ring conductors of the tandem trunk, whichreversal is translated into an increase of the yresistance on `thesleeve conductor of the A operators cord, resulting in the extinguishingofthe supervisory lamp.

An object of this invention is to provide a greatly improved arrangementin tandem trunk circuits, whereby this kind of supervision, which isordinarily termed high-low supervision, is effective over the talkingconductors ofthe A operators cord circuit 1nstead of over the sleeveconductors as heretofore. f

Another object ofthis invention is to provide that the application ofthe usual tandem trunk group busy tone is established by means of theabove mentioned supervisorycircuit arrangement without the aid of anyyadditional apparatus. -I`

To attain these and other objects of the invention, there is provided,in accordance with one feature thereof, a relay rarrangement, theoriginating Operations of which take place through the ring conductor ofan A cord and a tandem trunk when connected together without interferingwiththe usual lighting of thesupervisory lamp andso arranged that whenvthe called subscriber an-y swers, this relay arrangement is responsiveto the reversal of the current on the line to extinguish the supervisorylamp, through the Operation of the usual supervisory relay over the tipand ring conductors.

Another feature of the invention resides in this, that the above relayarrangement is may be reached.

HERBERT B. JOHNSON, OF BROOKLYN, NEW YORK, Ass'IGNOR TOHBELL TELEPHONELABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A coRPoR-ATIONOF NEWl VTELEPHONE sYsTRiilry 1925.- Sekrikal No.y 29,688. n i

also operative to apply a group busy tone On f i f the sleeve of thefirst tandem trunk if kall lines 1n a group of such trunks are busy.k

The following det-ail description of theine vention should'be read inconnection with the 1 accompanyingdrawing,fin which the outgoying endkofa tandem trunk, arranged inaccordance with this invention, is shown inconnection with a portion of an A operators cordat a localexchange,fwhile the incom` ing end of this tandem trunk is shown sche-`matically at atandem operators ,position kin a distant tandem exchangeWhere a portion of astandard trunk circuit leading to another y localexchange is shown in sufhcient detail to enable the proper descriptionof the invenr tandem ytrunk T; and the tandem operator TO at the tandemexchange, in answer to the usual signaling from the Ayposition, insertsplugk 3 of this tandem trunk into a jack L of the trunk TS leadingtoanother local exito the drawing, iny estabi change through whichthewanted subscriber Y The insertion kof plug yinto yjack 2 closes `acircuit for theA lighting of the supervisory' lamp 6 as follows:battery, lamp 6, sleeve .terminals of plug 1 and jack 2 to ground nothercircuitisr` through a resistancek 7.y

also completed `from the talking battery of `the A cord through thelowervright hand windingof the repeating coil 8, they super-y visoryrelay 9, the" ring'terminals of plugl andjackfQ, lower left'handwindingof repeatingy coil 10` fofr the tandem trunk, low

resistance winding` 11 and `highresistance. winding 12 of relay'13 inseries to ground.y This circuit causes the operation of relay 13, .butdueto the high resistance windingc12 of this' relay, the supervisoryy,relay 9 is notoperated at this time, thus permitting the sueration ofrelay 13 closes a circuit through the battery and lower armatureand backcontact of relay 15, lower winding .of relay 16,

pervisory lamp 6 to remain lighted. The Opy winding of the polarizedrelay Mas follows:

n ring conductor of trunk T, fright handlower winding of a repeatingcoil 10,-winding'of relay 1dr-, upper armature and front contactot'relay 13, upper right hand winding of refinding ot relayT 16, upperarmature back Contact ot relay to ground. VIteis polarized soas not tooperate on t urreut passii'rqv through its winding in t' J direction.,However, relay 16 operates icatic-ns to be given to the tandeinoperatorat. TG hat a through connection is desired.

Tnanswer to this indication, the tandem operator at .TO communicateswith the A operator and. on receivingthe-proper direction 4as to theextension of the connection inserts Vthe tip and ring leads through tothe trunk 'TS follows: from the upper armature and 'iront'contact ofrelay 15 through the tip terminals of plug 3 and jack fl, upper lefthand winding ot the repeating coil 18, left hand make-before-breakcontacts ofvrelay 19, left Y hand winding ot relay .toV ground and from*trunk v, frein the ,talkingibattery'fat V`the cord A' Y liroufhthelower'right hand winding of re-VV coily 3, thesuperviso'ry relay),the innalsoit plug 1 and jack V2, lowerY d Y'winding of repeating vcoil10, low

voit' the supervisory relay 21. `,op r ting closes an energizing circuitfor retlie lower armature Vand'iirontContact of relayi'l, over the ringterminals oit' plug 3 and jack fl, lower left hand winding of repeatfingcoil 13, right hand make-beore-break contacts oi relay 19 and right handwinding of relay 2O to battery. Relay 20 is now operated and, as is wellknown in the art, nidications are given at the distant local oflice,

(not shown) that a connection with a subscriber at this office iswanted.

lt'is now assumed that thewanted. subscriber is yconnected with and rungvin the usual manner and that the subscriber answers the call byremoving his receiver from the hook, l' This action on the part of thecalled subscriber will result in the operation Relay 21 in 19 whiclrnowreverses the battery supply iorpola ized relay 141- by the Voperation ofits armature 'in a manner which is believed to be oigcurr'ent and thusVshunts the high resistance winding 12 oi relay 13, aiidrbridges theAlowresisten'ce winding 11 of this relay acrossV the tip and -ringconduct-ors Aof the tandem ne, circuit vis thereby established Yresistance winding 11 ot relay 13, armature' and Vfront contact yofrelay A14, upper leftV liaiidwinding of repeating coil 1Q, tip terminaisot jackQ and plug 1, upper right hand in the usual manner, not shown, tocause in- K' armature and front Contact closing the shuntV to batterytor lamp 6 which is thereby eX- tinguished to indicate to the A operatorthat the subscriber at thedistance local exchange has answered the call.A

lt will be seen that, in accordance with this invention, the supervisionas described above is effective through the talking conductors of tandemtrunk circuit and the cord circuit and not as is the usual practicethrough the sleeve conductors. Y

Another featurefof the invention, which also is a step toward thesimplification of the control of circuits of this type, is theapplication of group busy tone on the first trunk in a group ofv trunks.This is accomplished by'means of an armature and front Contact on relayv13 of the various tandem trunks in a group ot trunks. 'For example, ifall the relays 13 ot'th'ese trunks are operated, a chain circuitl willbe completed'as shown from the tone sourceV 25 `connected to the lowerarmature and front contact of the relay 13 of the last* tandem trunk inthe group through the Y corresponding contacts of the relays 13 of theintermediate tandem trunks to the correspondingrarmature and frontContact of rel 13 on the first-trunk. Therefore, if all the while theapplication of trunk groupbusy4 tone is well known, the"arrangement ofthis feature in connection with the rsupervisory relay arrangement inthe manner described is 'exceedingly simple Yas noi. additionalapparatus isV required-except a singlei armature and contactY on therelay 13 of the various tandem trunks.'

What is claimed'is: y 1 In a telephone system, a cord circuit and a linecircuit having respectively tip ring# and sleeve conductors and acorresponding plugand jack, a signal and a circuit thereforYincluding'the sleeve conductors or" said cord circuit 'and line foroperating said signal on the insertion of tlieplug'into the ack, a su-V"resistance winding, a' circuit including the" 12 ring conductors andsaid high and low resistance lwindings for maintaining the supervisoryrelay in non-operated condition and for operating said second mentionedrelay,

pola'i'iz'ed'relay and a circuit therefor arranged to be closed on theoperation of the second mentioned relay, means for supplying battery tosaid last mentioned circuit for the operation of said polarized relayand a circuit controlled by said polarized relay to cause the operationof the supervisory relay over the tip and ring conductors by shuntingthe high resistance winding of the second mentioned relay.

2. In a telephone system, a cord circuit having tip, ring and sleeveconductors and a supervisory relay in said ring conductor responsive toa low resistance connection established from the said tip conductor tothe said ring conductor, a trunk line accessible to said cord circuithaving a polarized relay and a second relay having high and lowresistance windings, means for energizing said second relay upon theconnection of said oord circuit to said trunk in a circuit includingsaid supervisory relay and both said windings of said second relay inseries, and means controlled by said polarized relay for connecting thesaid lowr resistance Winding of said second relay across the tip andring conductors of said cord circuit.

3. In a telephone system, a cord circuit having tip, ring and sleeveconductors and a supervisory relay in said ring conductor responsive toa low resistance connection established from the said tip conductor tothe said ring conductor, a group of trunk lines accessible to saidcordcircuit, each said trunk line having individual thereto a polarizedrelay and a second relay having high and low resistance windings, meansfor energizing said second relay upon the connection of said cordcircuitfto said trunk in a circuit including said supervisory relay andboth said windings of said second relayv in series, means controlled bysaid polarized relay for` connectinrthe said low resistance winding ofsaid second relay across the tip andfring conductors of said cordcircuit, and means controlled byy all of said secondirelays of saidgroup of trunks for establishing an all-trunks-busy condition.

4. In a telephone system, a cord circuit having tip, ring and sleeveconductors and a supervisory relayin said ring conductor' responsive toa low resistance connection established from the saidv tip conductor tothe said ring conductor, a group of trunk lines accessible to said cordcircuit, each said trunk line having individual thereto a polarizedrelay and a second relay having high and low resistance windings, meansfor energizing said second relay upon connection of said cord circuit tosaid trunk in a circuit including said supervisory relay and both saidwindings of said second relay in series, means controlled by saidpolarized relay for connecting the said low resistance winding of saidsecond relay across the tip and ring conductors of said cord circuit,k a

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